My husband and I signed up for the new extended Hazel-Atlas mine tour at
Black Diamond Mines, and met our tour group at the Greathouse Portal. It was 90 degrees outside, but we felt refreshing cool air coming through the portal from deep inside the hill.
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| The Greathouse Portal - original entrance to the sand mine |
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| The Greathouse Visitor Center |
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| Warren of mine shafts |
After an introduction, we hiked about 15 minutes to the Hazel Atlas Portal, and the gated entrance to the Eureka Coal Mine. We learned about coal (the pressurized remains of peat from a vast inland sea), and the coal mining that took place from 1860 -1906 (miners came from all over the world, conditions were hard, and the hours long). Mining was finally stopped because the Mount Diablo Coalfield produced the lowest grade of coal, lignite.
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| The Eureka Slope - entrance to the Eureka Coal Mine |
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| Eureka Coal Mine |
We suited up with our hard hats and LED flashlights and hit the mines. We saw the office, where all workers and visitors checked in for safety. Everyone had to be accounted for in case of an accident in the mine.
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| Suited up and ready to tour |
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| The office |
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| Veins of coal running through sandstone |
Sand mining took place from 1920s -1940s. The sandstone produced silica that was almost 95% pure. It was used by the Hazel-Atlas Glass Company to manufacture bottles and jars in Oakland. The sand is very fine, so easy to see why it was selected for making glass.
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| Vein of coal running through the sandstone |
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| A chute for loading ore cars with sand |
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| A giant stope left from mining sand |
On the tour we saw cutaways of the veins of coal running through the sandstone. We also saw an earthquake fault which was interesting (and sobering). We were grateful for all the rock bolts and special steel-frames protecting the passages. Our tour guide pointed out stopes and chutes, and a mine car filled with sand.
Back at the Visitor Center we learned more about glass production.
My Example
We finished the tour at the small gift shop, perfect for "Black Diamond" coal specimens, pencils, and black licorice "coal". We finished the day with dinner and conversation at
Casa Orinda Restaurant, an original roadhouse known for fried chicken and biscuits and many other delicious menu items.
This is a wonderful tour for anyone interested in geology, mining, or history. You can order tickets
online, or buy them at the Greathouse Visitor Center (tours are small, so can sell out quickly).
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